Heat urea strainer for diesel engine

ABSTRACT

A urea strainer includes a mesh for removing impurities from urea passing therethrough and heatable wires to heat the urea as it passes through the mesh. The urea is provided to an emission control system of a diesel engine.

I. FIELD OF THE INVENTION

The present invention relates generally to simultaneously heating enginefluids and filtering the fluids, and more particularly to heated ureastrainers for diesel engines.

II. BACKGROUND OF THE INVENTION

Diesel engines are typically required by law to incorporate a method forreducing nitrous-oxide (NOx) emissions. To reduce the amount of NOxemitted, many diesel engines include what is known as SelectiveCatalytic Reduction (SCR) system. In an SCR system, a solution of ureaand water is injected into a catalytic converter, which is part of theemission control system of a diesel engine. When the urea-water solutioninteracts with the NOx, the NOx is converted into nitrogen gas (N2) andwater (H2O).

The SCR system therefore requires a urea delivery system whereby theurea may be transferred from a urea tank to the catalytic converter whennecessary. However, urea freezes at −11° C. In many parts of the worldin which diesel engines are used, typical winter temperatures can dipbelow −25° C. Thus, a method for melting urea so that it may be injectedinto a catalytic converter while in extreme weather conditions isnecessary. Currently, the predominant method for melting urea in an SCRsystem involves a coil heating element.

SUMMARY OF THE INVENTION

As recognized herein, it is unfortunately the case that theabove-mentioned coil heating element requires a high current draw fromthe diesel engine system, consuming energy that would be used elsewherein the diesel engine system. Further, the present application recognizesthat existing coils to melt urea are placed in a less than optimalposition in terms of efficiency. As understood herein, a heating elementshould be positioned as close as possible to a urea strainer.

Accordingly, a system includes a urea tank and a strainer through whichurea from the tank passes to an emission control system of a dieselengine. At least portions of the strainer can be heated to heat ureapassing through the strainer.

The portions may include wires that may criss-cross each other. Thestrainer may be disc-shaped, and the strainer removes impurities fromurea passing therethrough. Thus, the wires may be juxtaposed withmaterial in a mesh to remove impurities from urea. An electricalconnector can be provided that is configured for engaging a source ofelectricity. The connector is electrically connected to the wires.

In another aspect, an apparatus includes a strainer engageable with aurea tank associated with a diesel engine for chemically reacting withnitrogen oxide. The strainer includes plural elements removingimpurities from urea passing therethrough, with at least some elementsbeing heatable by electricity to heat urea. An electrical connector isconfigured for engaging a source of electricity. The connector iselectrically connected to at least some of the elements.

In another aspect, a method includes removing impurities from urea andheating the urea as the impurities are being removed therefrom.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram in accordance with one non-limiting embodimentof a diesel engine system;

FIG. 2 is a perspective view of a non-limiting embodiment of a ureastrainer capable of being heated to melt frozen urea; and

FIG. 3 is a top plan view of the urea strainer shown in FIG. 2, withportions of the housing removed to expose the interior strainer mesh.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is intended for application in automotive vehiclesystems and will be described in that context. It is to be understood,however, that the present invention could also be applied in other fueldelivery applications.

Beginning initially with FIG. 1, a diesel engine system 10 is shown. Thesystem 10 has a diesel engine 12 and a diesel fuel tank 14 whichdelivers diesel fuel to the engine 12 when necessary. Further, connectedto the diesel engine 12 is a catalytic converter 16, with the catalyticconverter 16 receiving emissions produced by the diesel engine 12.

Attached to the catalytic converter 16 is a Selective CatalyticReduction (SCR) system 18. The purpose of the SCR system 18 is to reducenitrous oxide (NOx) emissions created by the diesel engine 12 intonitrogen gas (N2) and water (H20). The SCR system 18 accomplishes thisby injecting urea into NOx produced by the catalytic converter 16. Whenthe urea interacts with the NOx, the NOx is converted into N2 and H2O.

Thus, the SCR system 18 requires a urea delivery system 20. The ureadelivery system 20 includes a urea tank 22 where urea may be stored, anda urea strainer 24 which, in accordance with principles explainedfurther below, is made up of an electrically resistive mesh compositioncapable of both filtering and melting urea. Further, the strainer 24 hasan energy source 26 which provides energy required by the strainer 24 tomelt urea in the tank 22. The energy source 26 may be the electricaldistribution system of a vehicle and may include a battery.

Further still, the catalytic converter 16 can be fluidly connected to awater tank 28. The water tank 28 may receive H2O from the catalyticconverter 16. Lastly, a muffler 30 is connected to the catalyticconverter 16. Remaining emissions from the treated effluent of thecatalytic converter 16, e.g., N2, may travel to the muffler 30, wherethe muffler 30 may then release the remaining emissions from the dieselengine system 10.

Moving to FIG. 2, a non-limiting embodiment of a urea strainer is shownembodied in a urea strainer assembly 32. The assembly 32 may be placedin a urea tank. The assembly 32 can include a hollow metal or plasticstrainer housing 34 and an outlet 36 formed on the housing 34 throughwhich urea may pass from a urea tank, with fluid passing from the tank,into an inlet (not shown) on the side of the strainer opposite theoutlet 36, and then to the SCR system 18 described above.

As set forth further below, the strainer in the housing 34 is at leastpartially composed of overlapping wires capable of being heated andcooled and may be submergible in liquid. The wires at least partiallycomposing the strainer 34 will be discussed in further detail in FIG. 3.

Continuing with FIG. 2, the assembly 32 also includes an electricalconnector 38 that is electrically connected to the strainer through atleast one wire 40. The wire 40 transmits electricity from the connector38 to the strainer 34, and the connector 38 can be connected to avehicle's electrical distribution system to thus send an electriccurrent to the strainer, which in turn may be resistively heated to meltfrozen urea.

Additional details of the assembly 32 are shown in FIG. 3. As may beseen in FIG. 3, the strainer housing 34 holds a resistive mesh 50 thatis at least partially composed of wires 52 which may be woven,overlapping, crisscrossing or the like. Further still, the wires 52 canbe substantially in the same plane and may be interwoven with anothermaterial in the mesh 50 such as fabric or plastic to remove impuritiesfrom urea passing therethrough, although in some embodiments onlyelectrically energizable wires, closely spaced, may be provided toundertake both the filtering and heating functions. When other materialsare included in the strainer 44 in addition to energizable wires 52, theother materials can not only provide structural support for thestrainer, but also help strain urea going into a urea tank. Thus, themesh 50 including wires 52 and other materials may form a disc withopenings in it for urea to be strained through.

Further still, the wires 52 may be excited by electricity from theconnector 38 to warm urea. Thus, in its heated state, the strainer meltsfrozen urea at the point where the urea is filtered. Further, anexternal temperature sensor located on a vehicle in a non-limitingembodiment may be used to determine when current should be sent from thepower source to the mesh 50 to melt frozen urea.

Moreover, the maximum temperature to which the strainer may be heatedmay vary depending on the materials composing both the mesh 50 thestrainer so as to not damage either the strainer mesh 50. Regardless,the position of the strainer relative to a urea tank optimizes energyconservation by reducing the electrical draw required to heat frozenurea in a urea tank.

It is to be understood that the present non-limiting embodiment may beused in other applications other than the filtering of urea. The presentinvention may be used in conjunction with diesel filtration systems orwindshield wiper filtration systems, for example.

While the particular HEATED UREA STRAINER FOR DIESEL ENGINE is hereinshown and described in detail, it is to be understood that the subjectmatter which is encompassed by the present invention is limited only bythe claims. For example, in addition to the above connection mechanisms,other quick connect/quick disconnect type of mechanisms may be used.

1. A system comprising: a urea tank; and a strainer through which ureafrom the tank passes to an emission control system of a diesel engine,at least portions of the strainer being heatable to heat urea passingtherethrough.
 2. The system of claim 1, wherein the portions includewires.
 3. The system of claim 2, wherein the wires criss-cross.
 4. Thesystem of claim 1, wherein the strainer is disc-shaped.
 5. The system ofclaim 1, wherein the strainer removes impurities from urea passingtherethrough.
 6. The system of claim 2, wherein the wires are juxtaposedwith material in a mesh to remove impurities from urea.
 7. The system ofclaim 2, comprising an electrical connector configured for engaging asource of electricity, the connector being electrically connected to atleast some of the wires.
 8. Apparatus comprising: strainer engageablewith a urea tank associated with a diesel engine for chemically reactingwith nitrogen oxide, the strainer including plural elements removingimpurities from urea passing therethrough, at least some elements beingheatable by electricity to heat urea; and an electrical connectorconfigured for engaging a source of electricity, the connector beingelectrically connected to at least some of the elements.
 9. Theapparatus of claim 8, wherein the elements include wires.
 10. Theapparatus of claim 9, wherein the wires criss-cross.
 11. The apparatusof claim 8, wherein the strainer is disc-shaped.
 12. The apparatus ofclaim 9, wherein the wires are juxtaposed with material in a mesh toremove impurities from urea.
 13. Method comprising: removing impuritiesfrom urea; and heating urea as the impurities are being removedtherefrom.
 14. The method of claim 13, comprising providing the urea toa diesel engine emission control system.
 15. The method of claim 13,comprising a providing a strainer purifying and heating the urea. 16.The method of claim 15, wherein at least portions of the strainer areheatable to heat urea passing therethrough.
 17. The method of claim 15,wherein the strainer is disc-shaped.
 18. The method of claim 15,heatable wires of the strainer are juxtaposed with material in a mesh toremove impurities from urea.
 19. The system of claim 18, comprising anelectrical connector configured for engaging a source of electricity,the connector being electrically connected to at least some of thewires.